Step 15: Other Transistor Things...

Step 16: How to Wire It Into Your System

The last thing to do is break out the screwdriver and wire it into the system. Along with the diode.Remove the Positive wires of both the solar panel...

While I love making proof of concept solar projects, or solar projects that I might use if the world comes to an end, I prefer to make solar projects that are useful in my day to day life. (I love my solar FM radio, but I've never had the need to use it in an emergency situation)

This past summer my father had been complaining about installing a lighting system for the back of his yard. The big issue being that he hates running wire 100 yards just to get three lights to turn on at night. Plus, being the over achiever that he is, he decided to bury the wires so that he wouldn't run over them with the lawn mower. This is when I stepped in.

I decided to make a high powered solar lighting system so no wires would ever need to be run to the back of the yard. Ever.

Oh, and I'm not talking about a few little wussy LEDs inside of a jar, I'm talking some high powered 3 watt LEDs inside real metal lighting enclosures. Ones that will probably attract every moth for ten miles. (And in defense of LEDs in jars, I happen to have 12 of those on the deck of my apartment. A couple slowly pulsing in and out.)

So for your enjoyment, here is a quick, easy, and inexpensive guide to making a high powered solar lighting system.

(If you like my project, vote for it in the Off The Grid Contest here at instructables, I'm the first entry. Seriously. A vote for me will bring you instant karma and a warm fuzzy feeling. WARNING: Warm fuzzy feeling may in fact be low levels of radiation. Seek medical help.)

I know this is an old thread, but I am not sure where else to post my question. I acquired an old gas streetlight which I want to install in my front yard. I don't want to run electric for a conversion and gas would not be an option either. Would like to create a nice looking interior light that is solar but I don't want a huge panel sitting on top to ruin the antique fixture. I do not need a tremendous amount of light--maybe equal to a 40-60 watt incandescent? I would like a really nice attractive light similar to a candle or like the gas light looked. I have no idea where to get parts or instructions for this so I came across this thread and joined so I could ask someone to help if they can. I'm looking for something unique and classy to go with the beautiful exterior of this old light. Thanks!

I have been wracking my brain to work out a system like this. I need some bright light in the driveway and in the back yard. I can easily avoid the weather in both areas by placing the box of tricks under the roof, and the lights on either end of my boat shed, with the solar panel on top of the roof. However, the piddly little garden lights would be useless for my situation. I wonder now if I can become an electrician. At least a hobbyist type. Thanks for this one, it is great.

Well sweet. I'm glad it came in handy for you. Solar system are rather simple once you learn what everything is and how they interact together. I'm no master electrician, just a simple hobbyist, and learning how to use solar in my projects was the best thing I ever did.

very interesting I have been doing optics since 92 and wonder if we could talk sometime my name is Mark Zimmerman and I go by the name optichead I need some fine tuning for a new garden system Im at sealwizene@aol.com

Very well done mate. How is the thing holding up? I'm worried about the heatsinks on the LEDs (They seem tiny), Are they adequate? or Could we use some interface that enables whole enclosure as an heatsink?

This would be a great situation to use an ATtiny 85 - small and cheap, it could measure the voltage from the solar panel to do your dark detecting and also control any fancy functions, like fading or blinking. You could also set it up to give full light for the first few hours of darkness (for show) and then just a little light during the rest of the night to find your way around!

I love the idea of massive, powerful things controlled by little tiny controllers running your home-written firmware, and this is the perfect setup for it - you have a PWM control input, you have +5V and the solar-cell voltage available. All you need is an ATTiny and a breakout board!

Another option for the dark detection would be simply to use the PWM pin of your controller with a simple pull down resistor and a low power transistor. Depending on the voltage limits of your controller's PWM pin, you could use essentially the same circuit you did here except the transistor would be feeding the PWM pin instead of the LEDs.

As a side note, isnt the 2N3904 you mention a NPN transistor? The way your circuit works, a PNP transistor is needed (as you correctly said so in your text and circuit drawing). It might be good to change the reference to the complementary 2N3906 (PNP) or to simply state the it is a NPN. That way, the less knowledgeable that dont need high power are not misled into using a transistor that would not work in this application (NPN would always be on).

Joshua: OK on your comments, & I certainly appreciate the regulator's function. With only a dusk-midnight need you may well want to include a simple timer too. How about using the likes of a PICAXE micro => www.picaxe.orcon.net.nz ? These are a dream for pre-teens!

Mmm- given your freezing Wisconsin winters an additional aspect may relate to lead acid batteries poor performance when cold/chilled. Best wrap up that poor SLA to keep it cosy!

Happy to point out this SLA "Gel Cell" source,especially as you're a teacher with (no doubt) a cash strapped budget. Being sealed they present no fume or acid spill concerns of course. Sigh-if only they'd been available when I was younger. Back in my teens I recall rescuing a regular flooded car battery & building it into bench power supply, with resulting sulfuric acid "migration"-argh!

Discarded SLA batteries are usually just sent for scrap metal, & (even with the present value of lead) only bring in about US$1-$2 each. This may be hardly worthwhile for the security firm to bother with, so you could perhaps even make some science resource "pocket money" by offering to do it for them. Play up your educational needs of course.Hence rescue quite a swag, use the good ones (or pass to capable students/friends) & take the really weary ones in for scrap $$ yourself. It sure beats collecting aluminum drink cans.

Health & Safety ALERT: 12V 7Ah SLAs are VERY energetic & start a fire if shorted, and even jump start a car, or power an e-bike/scooter etc. I once gave a 12V 7Ah SLA to a 12 yo. who'd looked a budding bright spark. Word filtered back to me however that he'd just used it to "make a bomb" by shorting the terminals with a heavy duty cable, to then relish the resulting acrid smoke & fumes as the battery destructed... I now only pass out the smaller 12V 2Ah types when in doubt about the end user's motives.

Extra: A simple charge confirmation indicator can be VERY worthwhile too -at the least it confirms connections haven't come adrift or terminals corroded. I've done a bit in the past with FLEDs ( Flashng LEDs) for this in fact (See Instructable => www.instructables.com/id/Single-LED-ammeter-FLED-based/ ) & the attached relates to one a student of mine recently used for a similar (but switched) LED lighting project.

The addition of a pull down resistor on the transistor's base shouldn't hinder the function of this circuit however it may not be necessary. PV cells loose their voltage during darkness, that is why you need a blocking diode to stop your batteries from discharging through the panel, this lower voltage should in theory be enough to power the transistor.

By the looks of it I'd guess your solar PV is rated at 10 Watts? Thus with an average of 4 hours bright sun daily the battery will receive approx. half a charge each day. However a 3W LED could be on for 10-12 hours each night, & more in winter. A few days of gloom would mean the battery near drained & it's life possibly greatly reduced!! With such a lighting load you may hence need a larger PV, or more batteries...

Handy hint: Check a local security firm for free SLA ( Sealed Lead Acid) "discards". Here in NZ such contacts supply more than I can handle - they're ideal for my educational work. Such 12V 7Ah batteries are a global standby standard & firms often renew them at critical sites every couple of years to ensure reliability.. In less demanding applications they'll usually still be good for 5-8 years if not allowed to go flat or discharged too deeply.

FWIW even 20W PVs,c/w inbuilt controller, are often now under US$50 in the right places.

Oh, and you don't have to worry about the battery every completely draining! Thats what the solar charge controller is for. When the battery hits a certain "low" voltage the charge controller cuts off the "load." I always recommend people spend the $10-20 for one in order to save their batteries from excess wear and tear.

I promised my Dad I would make this for him last summer. I even had all the parts sitting in my basement for the past year. I'm glad I waited because I learned quite a bit during that time which helped me with this project. I could have done it, but not as nicely.

If you go with some cheap 1W LEDs and a low cost driver and charge controller, the project's price tag is between $50-100. The biggest issues are the cost of the solar panel and the battery. I got my battery on sale for $10, it's normally $20ish. Same with the solar panel, a random online sale last year.

It's not an overly difficult project, but it does take some time to find and order all the parts. I made a third "head" the other evening and it took all of 10 minutes to do and wire into my setup.

It a very easy addition, and I hope the parts come today. I'll add that bit into the guide. All it requires is soldering a transistor, a resistor, and three wires together. While not the most efficient, it is cheap and easy.

I've been using the same design when I make small scale garden lights or projects. I've even used it in past instructables, though I can not take credit for the idea. I believe I got it from evilmadscience.com a couple of year ago.

From start to finish about 2 and a half hours. I was also taking photos at the same time, which added a bit into the mix.

A big chunk of my time was figuing out how to make all my wires "fit" into various things. Such as running the wire up into the metal heads, or connecting to the battery. The "hard" work was quick and easy.

If I was to do this a second time I'm guessing I could do 3 heads in around an hour and a half to two hours.